[Proposal] Using [] for indexes, ranges, and limiting type ranges

Dealing with Small Basic, I became a fan of using `[]` for indexing collections (`a[0]`), and I want this to be optional in VB.NET besides `()` (`a(0)`).
This will allow us also to use ranges:
`Dim a = [1 To 5] ' a = {1, 2, 3, 4, 5}`
`If x in [1 To 5] Then'
Which is optimized to:
`If x >= 1 AndAlso x <= 5 Then'
And even restrict value types range
```
Dim x as Integer[100 To 1000]`
x = 1001 ' Exception
```
Which will be lowered to
```
Dim x as Integer
Sub Set_[LOCALID]_x(value as integer, )
If 1001 >= 100 AndAlso 1001 <= 1000) Then
x = 1001
else
Throw New OutOfRangeException()
EndIf
End Sub
```

Any assignment to x will be replaced with such checks. If x is paced byref, then we will pass a temp var instead, then do the same check before assigning the temp val to x.

We can do the same for function params, and property setters.